420 Transactions. — Geology. 



Large bodies of marble rock resembling that from Caswell 

 Somid, and certainly not inferior to it, are found not far 

 distant from the copper-lode, and near Rugged Island there 

 are large deposits of manganese-oxide. 



South of Paterson's Inlet for the most part the country is 

 formed of a soft grey granite, but there are belts of other rocks 

 associated therewith, consisting of gneiss and mica rock, 

 schistose or granular, and, in the Tin Range, very considerable 

 bodies of a quartzose rock having a granular texture. 



The typical granite rock is highly felspathic, and weathers 

 into remarkable conical or dome-shaped mountains, of which 

 Lee's Knob, on the east side of the main range and five miles 

 north of Port Pegasus, is a remarkable example. The Deceit 

 Peaks, to the west of the main range, are formed of the same 

 rock, but have not the same regularity of outline as the granite 

 hills on the east side. 



Towards the southern extremity of the island, and west of 

 the south arm of Port Pegasus, are two isolated mountains, 

 called respectively Gog and Magog, which are also formed of 

 granite, and are remarkable objects in the landscape. 



The granite, where I examined it most carefully, towards 

 the northern end of the Tin Range and in Lee's Knob, has 

 numerous strong veins of felspar, and felspar and mica mixed. 

 Small garnets abound in some parts, and there is a great 

 abundance of glassy quartz closely approaching rock-crystal, 

 which chiefly occurs in nests and segregations in the felspathic 

 veins. The gneissic rocks are well seen on the shores of the 

 north arm of Port Pegasus, more especially in a small bay 

 three-quarters of a mile east of the landing-place. 



At the head of this small bay there is, on its west side, a 

 heavy reef of qiiartz full of iron-sulphide and traces of copper. 

 Samples of this reef, known as Cross's Reef, I was informed 

 had been sent to Melbourne, and, as reported, gave 5dwt. of 

 gold and 13dwt. of silver to the ton. I tested for gold, but 

 found none. This reef runs nearly east and west, and, on the 

 opposite (eastern) side of the small bay, about one chain 

 distant, it is seen to have greatly changed in character, and to 

 be for the most part composed of felspar. 



At the landing-place, survey-camp, and beginnings of the 

 township that is to be, the rock is granite, with small veins of 

 glassy quartz. At the head of the north arm of Port Pegasus, 

 and along the lower course of Pegasus Creek, the rocks are 

 schistose, with bands of pure mica rock, and reefs of quartz, 

 felspar, and mica, or, in other words, the elements of granite ; 

 but the minerals are so coarsely crystallized, and the crystals 

 so free of entanglement among each other, as is the case with 

 normal granite, that one scarcely inclines to speak of such a 

 rock as a granite. 



